There are numerous operations that take place in a sawmill for converting logs to graded lumber. As the lumber pieces are formed out of the logs, they are conveyed from operation to operation, e.g., for trimming, edging, etc. It is important in the conveyance of the lumber pieces to properly orient those pieces when being directed into successive operations.
For a number of reasons, as the lumber pieces are being conveyed from one operation to the next, they become piled in a disarrayed arrangement. Before the lumber pieces can be efficiently processed in the next operation, the piled pieces must be reorganized (sometimes referred to as unscrambled). Machines known as unscramblers typically employ a V shaped trough or bin. The scrambled lumber pieces are dropped into the trough and as they bottom in the crease of the V they become aligned with the crease and, therefore, with each other. A conveyor with lifting bars pulls the pieces (supposedly sequentially) out of the trough bottom and the successive lumber pieces are thereby aligned, i.e., they retain the orientation of the crease in the bottom of the trough.
The problem with the unscramblers as described above is basically two-fold. The lifting bars of the conveyor need to be sized to the lumber being handled. If they are too small, they will not lift the larger pieces. If they are too big, they will lift out multiple smaller pieces which is also undesired. Also, the procedure of dropping the lumber into the trough and sequentially lifting them off of the bottom causes damage to the pieces. In the lift out procedure, when the trough contains a number of lumber pieces, because the bottom ones are being lifted out, the pieces piled on top are tumbled. Both the dropping of the pieces into the trough and the tumbling of the pieces by the lift out conveyor causes damage and reduces the value of the lumber.